Exchange and transport in animals Flashcards
What happens to the SA:V ratio when organisms get bigger?
The ratio gets smaller
What does a smaller SA:V ratio mean for organisms?
Cannot rely on diffusion and need to have specialised exchange surfaces and transport systems
Where is oxygen exchanged and why?
In the alveoli in the lungs; needed for respiration
Where is carbon dioxide exchanged and why?
Alveoli in lungs; waste product of metabolism
Where is water exchanged and why?
Nephrons in kidney; needed for cells to function properly
Where are dissolved food molecules exchanged and why?
Small intestine; needed for respiration
Where are mineral ions exchanged and why?
Small intestine; needed for cells to function properly
Where is urea exchanged and why?
Nephrons in kidney; waste of metabolism
Why do flatworms does not have a transport or exchange system?
Flatworm is very thin and flat so has a large SA:V ratio and so diffusion occurs at a much greater distance
What factors affect the rate of diffusion?
- SA (larger SA, faster diffusion)
- Concentration gradient (bigger difference in concentration, faster diffusion)
- Distance to move (substances move more quickly if they haven’t got far to move)
What does Fick’s law state?
Rate of diffusion ∝ (SA X Concentration difference)/Thickness of membrane
What does a.u. stand for?
Arbitrary units
Describe gas exchange in the alveoli
- Air breathed in
- CO2 in blood from body produced by respiring cells and very little O2
- O2 diffuses across capillary membrane out of alveolus and enters red blood cells
- O2 carried round the body in red blood cells
- Body cells use up O2 in respiration
- Body cells produce CO2 in respiration and is carried to the lungs
- CO2 diffuses into the alveolus and is breathed out
- Air breathed out
Why is the alveoli folded?
Increases SA for gas diffusion
What are alveoli?
Tiny air sacs in the lungs
Describe how arteries pump blood
- Muscle fibres are stretched
- They contract and press inwards
- Helps push blood towards capillaries
- Stretching and contracting causes pulse which can be felt at wrist and neck
Why do veins only have a thin layer of muscle fibres?
For efficient diffusion
What do the valves in the vein do?
Stop blood flowing away from the heart
Describe how the valves in veins contribute to blood flow to and from heart
- Open like double doors to let blood flow towards heart
- Close to stop blood flowing away from heart
Describe the structure of capillaries
- Very small blood vessels
- Very thin walls so substances can go through thin walls of a capillary
Which blood vessels carry blood back to the heart?
Veins
Which blood vessels go between the cells of the body?
Capillaries
Which blood vessels carry blood away from the heart?
Arteries
Describe how the three blood vessels carry blood to and from the heart
- Heart pumps blood into arteries
- Arteries carry blood away from heart
- Arteries divide into very thin vessels called capillaries
- Capillaries go between cells of the body
- Capillaries join up to make veins
- Veins have valves in them
- Veins carry blood back to the heart
What is the equation for respiration?
Glucose + Oxygen -> Water + CO2 + Energy
In which blood vessel is the blood pressure the highest?
Arteries
What does the relaxation of muscle in arteries reduce?
Reduces the variation in blood pressure and males blood flow smoothly
In which blood vessel is the blood pressure the lowest?
Veins